How Does the International Space Station Fulfill Its Energy Needs

Solar energy is a big deal on planet Earth right now. People around the world have discovered its benefits. It’s clean, renewable, and increasingly affordable. Once you have a solar array in place, you can power your home or business for decades.

Solar helps us off-planet just as much as it does at home. The sun is our most plentiful power source, and scientists and researchers have found ways to tap into it aboard the International Space Station (ISS). If you’ve ever wondered how does the space station fulfill its energy needs, the answer lies in our closest star.

The Sun is the Answer

The International Space Station orbits about 400 kilometers (250 miles) above Earth’s surface. That’s far too great a distance to run a wire—especially to an enormous structure that is constantly moving. Instead of storing or transporting energy from Earth, engineers developed ways to gather it in space using solar power.

The ISS is an incredible feat of engineering. It has a mass of over 450,000 kilograms (990,000 pounds) and measures more than 110 meters (360 feet) in length. With a pressurized volume roughly equal to a Boeing 747, it remains the largest man-made object ever launched into space.

This collaborative marvel was built with the help of over 20 countries and has cost more than $150 billion USD, with billions more spent each year on operations and maintenance.

The ISS completes one orbit around Earth every 90 minutes. To put that in perspective, while 100 km/h (65 mph) may seem fast on a highway, the space station travels at a staggering 28,000 km/h (17,500 mph)—about 7.7 kilometers (4.8 miles) per second.

A Manmade Solar System in Space

Powering the ISS is not just a matter of convenience—it’s a matter of survival. Electricity is needed to run experiments, provide lighting, maintain life support systems, and keep the station habitable.

Solar energy is a logical choice in space. It’s abundant and continuous from a human perspective. The ISS is equipped with an extensive set of solar arrays. These were originally designed to fold like an accordion, protecting them during launch. Once the ISS reached orbit, ground controllers used radio signals to deploy the arrays safely.

Mounted on rotating gimbals, the arrays are able to track the sun as the station orbits Earth, optimizing efficiency. Each of the original arrays measured 34 meters (112 feet) in length and 12 meters (39 feet) wide, giving the ISS a total solar “wingspan” of 73 meters (240 feet). These panels contain 262,400 solar cells and cover an area of 2,500 square meters (27,000 square feet).

But that’s not the full story today. Starting in 2021, NASA began installing iROSA (roll-out solar arrays) on the ISS to supplement and enhance the original panels. These newer arrays are smaller, more efficient, and designed to partially overlay the older ones. Once fully deployed, they’ll increase the station’s power generation capacity from around 90 kilowatts (kW) to up to 120 kW.

To distribute this power, the ISS has about 13 kilometers (8 miles) of electrical wiring. Excess electricity generated during sunlight passes is stored for later use—especially important when the station passes into Earth’s shadow.

Modern Batteries for a Modern Station

Initially, the ISS used nickel-hydrogen batteries to store excess solar energy. Between 2017 and 2021, these were replaced with lithium-ion batteries, which are lighter, more efficient, and longer-lasting.

Now, approximately 60% of the electricity generated by the solar panels is stored for later use. These batteries are crucial for maintaining operations during the roughly 35 minutes of every orbit when the ISS is in darkness.

This modern energy system not only keeps the lights on—it sustains life, powers research, and ensures the ISS can function 24/7.

Looking Ahead

As we continue exploring space, the lessons learned from the ISS’s solar systems will help inform new missions. NASA’s Gateway lunar space station, set to support Artemis missions to the Moon, will rely on similar solar power systems. Innovations developed aboard the ISS will ripple outward—powering humanity’s next great journeys.

How does the space station fulfill its energy needs? The answer is bright, reliable, and 150 million kilometers away. It’s the same sun that powers homes on Earth—and it may be the key to powering our future in space.